diff mbox series

[v5,1/4] panic: Taint kernel if tests are run

Message ID 20220702040959.3232874-1-davidgow@google.com
State Superseded
Headers show
Series [v5,1/4] panic: Taint kernel if tests are run | expand

Commit Message

David Gow July 2, 2022, 4:09 a.m. UTC 
Most in-kernel tests (such as KUnit tests) are not supposed to run on
production systems: they may do deliberately illegal things to trigger
errors, and have security implications (for example, KUnit assertions
will often deliberately leak kernel addresses).

Add a new taint type, TAINT_TEST to signal that a test has been run.
This will be printed as 'N' (originally for kuNit, as every other
sensible letter was taken.)

This should discourage people from running these tests on production
systems, and to make it easier to tell if tests have been run
accidentally (by loading the wrong configuration, etc.)

Acked-by: Luis Chamberlain <mcgrof@kernel.org>
Reviewed-by: Brendan Higgins <brendanhiggins@google.com>
Signed-off-by: David Gow <davidgow@google.com>
---
 Documentation/admin-guide/tainted-kernels.rst | 1 +
 include/linux/panic.h                         | 3 ++-
 kernel/panic.c                                | 1 +
 3 files changed, 4 insertions(+), 1 deletion(-)

Comments

David Gow July 2, 2022, 4:45 a.m. UTC | #1 
On Sat, Jul 2, 2022 at 12:10 PM David Gow <davidgow@google.com> wrote:
>
> Taint the kernel with TAINT_TEST whenever a test module loads, by adding
> a new "TEST" module property, and setting it for all modules in the
> tools/testing directory. This property can also be set manually, for
> tests which live outside the tools/testing directory with:
> MODULE_INFO(test, "Y");
>
> Reviewed-by: Luis Chamberlain <mcgrof@kernel.org>
> Signed-off-by: David Gow <davidgow@google.com>
> ---

I forgot the changelogs here. The only significant difference from v4
is the change from pr_warn() to pr_warn_once().

Changes since v4:
https://lore.kernel.org/linux-kselftest/20220701084744.3002019-2-davidgow@google.com/
- Use pr_warn_once() to only log a warning the first time a module
taints the kernel with TAINT_TEST
  - Loading lots of test modules is a common usecase, and this would
otherwise spam the logs too much.
  - Thanks Luis.
- Remove a superfluous newline (Thanks Greg)
- Add Luis' Reviewed-by tag.

This patch was new in v4 of the series.
diff mbox series

Patch

diff --git a/Documentation/admin-guide/tainted-kernels.rst b/Documentation/admin-guide/tainted-kernels.rst
index ceeed7b0798d..7d80e8c307d1 100644
--- a/Documentation/admin-guide/tainted-kernels.rst
+++ b/Documentation/admin-guide/tainted-kernels.rst
@@ -100,6 +100,7 @@  Bit  Log  Number  Reason that got the kernel tainted
  15  _/K   32768  kernel has been live patched
  16  _/X   65536  auxiliary taint, defined for and used by distros
  17  _/T  131072  kernel was built with the struct randomization plugin
+ 18  _/N  262144  an in-kernel test has been run
 ===  ===  ======  ========================================================
 
 Note: The character ``_`` is representing a blank in this table to make reading
diff --git a/include/linux/panic.h b/include/linux/panic.h
index e71161da69c4..c7759b3f2045 100644
--- a/include/linux/panic.h
+++ b/include/linux/panic.h
@@ -68,7 +68,8 @@  static inline void set_arch_panic_timeout(int timeout, int arch_default_timeout)
 #define TAINT_LIVEPATCH			15
 #define TAINT_AUX			16
 #define TAINT_RANDSTRUCT		17
-#define TAINT_FLAGS_COUNT		18
+#define TAINT_TEST			18
+#define TAINT_FLAGS_COUNT		19
 #define TAINT_FLAGS_MAX			((1UL << TAINT_FLAGS_COUNT) - 1)
 
 struct taint_flag {
diff --git a/kernel/panic.c b/kernel/panic.c
index a3c758dba15a..6b3369e21026 100644
--- a/kernel/panic.c
+++ b/kernel/panic.c
@@ -428,6 +428,7 @@  const struct taint_flag taint_flags[TAINT_FLAGS_COUNT] = {
 	[ TAINT_LIVEPATCH ]		= { 'K', ' ', true },
 	[ TAINT_AUX ]			= { 'X', ' ', true },
 	[ TAINT_RANDSTRUCT ]		= { 'T', ' ', true },
+	[ TAINT_TEST ]			= { 'N', ' ', true },
 };
 
 /**